Although he had a noticeable accent on "Barney Miller" (1975) and "Sanford and Son" (1972), Sierra appeared in the "All in the Family" (1971) episode "Archie is Branded" without any accent at all.

He is familiar to fans of Barney Miller as Detective Sergeant Chano Amenguale, and as Julio Fuentes, the Puerto Rican neighbor on Sanford and Son, where his character was often the brunt of racist insults and jokes via the show's main character, Fred G. Sanford (portrayed by Redd Foxx).